1. Field of the Invention
The present invention relates to a semiconductor device. More specifically, the present invention relates to a semiconductor device of a resin sealing type having more pins and a smaller semiconductor pellet.
2. Description of the Prior Art
A semiconductor device has a large space between the edges of inner leads and an island due to a request for more pins of a PKG and a smaller semiconductor pellet.
FIG. 7 is a diagram showing a prior art semiconductor device in the state that a semiconductor pellet is fixed onto a lead frame and the electrodes of the semiconductor pellet and the edge parts of inner leads are connected by bonding wires in which FIG. 7A is a plan view and FIG. 7B is an enlarged plan view enlarging a part 210 indicated by the dotted line of FIG. 7A. Other three hanger leads and their peripheral parts have the same structure.
In FIG. 7, an island 1 fixing and mounting a semiconductor pellet 2 is supported by four hanger leads 3. Inner leads 5 of a lead frame 200 are extended in the island direction. As indicated by the phantom line arrows, the many inner leads 5 are arrayed at a fixed pitch at each side of the island 1 and surround the island 1. The edge parts of all the inner leads 5 and the electrodes of the semiconductor pellet 2 are connected by bonding wires 4. As indicated by the phantom line arrows, the arrayed bonding wires 4 also surround the island 1.
FIG. 8 is a plan view sequentially showing a resin flow in the prior art when the assembly in the state of FIG. 7 is sealed by a resin 7. FIG. 9 is a cross-sectional view enlarging Exe2x80x94E part of FIG. 8A.
Generally, a resin is filled first into a larger filling part. As shown in FIG. 8A, in the case of the shape of the lead frame of FIG. 7, a resin is filled first between the lead edges and the island (pellet mounting part). The resin is filled first into this part, and is then filled into the top/bottom surfaces of the pellet. The resin is filled into the peripheral part before being filled into the pellet. An air bubble 20A occurs on the top surface of the chip (FIG. 8B). At the completion of the filling, a void (bubble) 20B occurs without crushing the air bubble. The resin is hardened while the void exists. The semiconductor device has an insulation problem (FIG. 8C).
In the prior art, the resin is filled first into the larger part. As shown in FIG. 9, the resin 7 is filled first into the bottom surface side of the bonding wires 4 in a mold 15. To eliminate the filling difference, the resin 7 moves the bonding wires 4 upward to push away the bonding wires 4. At the movement, wire deformation, that is, undesired movement of the bonding wires occurs.
In the prior art, the resin filling difference between the top surface of the smaller semiconductor pellet with the thinner PKG and the inner lead edges-island is larger. A void (crack and gap) can be easily produced. The wire deformation due to the long wire can easily occur.
In the prior art, due to the thinner PKG, the filling difference between the chip and the chip-island easily occurs. From this point, the wire deformation occurs more easily.
Japanese Patent Application Laid-Open No. Hei 10-340976 (hereinafter, referred to as a first known technique) discloses a technique in which a control plate controlling resin flow is provided at the frame side in a part adjacent to the gate of a lead frame, thereby reducing void/wire deformation/pellet shift. In the first known technique, an angled control plate is provided at the gate side of the lead frame so as to eliminate the filling difference between the top and bottom parts of the PKG.
Japanese Patent Application Laid-Open No. Hei 5-152501 (hereinafter, referred to as a second known technique) discloses a technique in which a recess part is provided in an island part opposite the recess part (eject part) of the surface of a PKG so as to easily fill a resin without reducing the space between the eject part and the island part.
As described above, in the prior art shown in FIGS. 7 to 9, the resin filling difference between the top surface of the semiconductor pellet and the inner lead edges-island is larger. A void is easily produced and the wire deformation due to the long wire easily occurs. Due to the thinner PKG, the filling difference between the chip and the chip-island easily occurs. From this point, the wire deformation easily occurs.
In the first known technique, even when the filling difference between the top and bottom parts of the PKG can be reduced to some extent, it is impossible to reduce the resin filling difference between the pellet part and the inner lead edges-island and the resin filling difference between the top and bottom parts of the wires. The type in which the inner leads are formed near the gate cannot obtain a space providing the control plate.
In the second known technique, the resin flow at the lower side of the island is only improved. The problem arising from the fact that the resin filling difference between the top surface of the semiconductor pellet and the inner lead edges-island is large cannot be solved.
A semiconductor device of the present invention has an island; a semiconductor pellet fixed onto the island; many inner leads extended to the island; a resin sealing the island, semiconductor pellet and inner leads; and resin flow control plates provided between the edges of the inner leads and the island.